Solid state image pickup apparatus and method for manufacturing the same

ABSTRACT

When forming a hollow portion between each color filter, in order to realize the formation of the hollow portions with a narrower width, a plurality of light receiving portions are formed on the upper surface of a semiconductor substrate, a plurality of color filters corresponding to each of the light receiving portions are formed above the semiconductor substrate, a photoresist is formed on each color filter, side walls are formed on the side surfaces of the photoresist, and a hollow portion is formed between each color filter by performing etching using at least the side walls as a mask.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid state image pickup apparatus(solid state image pickup element), such as a CCD sensor and a CMOSsensor, and a method for manufacturing the same.

2. Description of the Related Art

For the solid state image pickup apparatus, a technique for increasingthe light collecting efficiency to light receiving portions,particularly a technique for more efficiently collecting light withsharp incident angle, has been expected. For example, Japanese PatentLaid-Open No. 2006-295125 has proposed a solid state image pickupapparatus having a structure in which hollow portions are formed inregions equivalent to the circumference of light receiving portions tothereby increase the light collecting efficiency to the light receivingportions utilizing the reflection on the interface of the hollowportions.

Specifically, Japanese Patent Laid-Open No. 2006-295125 discloses atechnique for forming the above-described hollow portion between eachcolor filter provided above each light receiving portion in such amanner as to correspond to each light receiving portion.

More specifically, according to Japanese Patent Laid-Open No.2006-295125, for the formation of the above-described hollow portion,first, a photosensitive resin layer is formed on a color filterformation film, and then the photosensitive resin layer is selectivelyexposed to thereby form a photoresist containing the photosensitiveresin layer. Then, etching using the photoresist as a mask is performedto form grooves in the color filter formation film to thereby form aplurality of color filters and also form the hollow portion between eachcolor filter.

However, due to the exposure limit of the photoresist (i.e., limitationby the minimum pattern when developing the photoresist), there has beena limit in narrowing the opening width of the photoresist. According tothe technique of Japanese Patent Laid-Open No. 2006-295125 describedabove, there has been a limit also in narrowing the width of the hollowportion formed between each color filter. For example, according to thetechnique of Japanese Patent Laid-Open No. 2006-295125 described above,it is difficult to form a hollow portion with a width of about 0.1 μm.Thus, when it is difficult to narrow the width of the hollow portionformed between each color filter, the area occupied by the color filterper pixel becomes small, so that a concern about a reduction in lightdetection sensitivity by the light receiving portions arises.

SUMMARY OF THE INVENTION

The present invention has been made in view of such problems and aims atproviding a method for manufacturing a solid state image pickupapparatus which achieves the formation of a hollow portion with anarrower width when forming the hollow portion between each colorfilter. The present invention also aims at providing a solid state imagepickup apparatus in which a hollow portion with a narrower width isformed between each color filter.

A method for manufacturing a solid state image pickup apparatus of theinvention includes a process of forming a plurality of color filterscorresponding to each light receiving portion above a semiconductorsubstrate in such a manner as to contact each other, a process offorming a photoresist having openings above the plurality of colorfilters, a process of forming side walls on the side surfaces of thephotoresist, and a process of forming a hollow portion between eachcolor filter by performing etching using at least the side walls as amask.

Another method for manufacturing a solid state image pickup apparatus ofthe invention is a method for manufacturing a solid state image pickupapparatus in which a plurality of light receiving portions are providedon the upper surface of the semiconductor substrate and includes aprocess of forming a plurality of color filters corresponding to eachlight receiving portion above a semiconductor substrate in such a manneras to contact each other, a process of forming a hard mask on theplurality of color filters, a process of forming a resist pattern havingfirst openings on the hard mask, a process of heat treating the resistpattern to form an etching mask having second openings whose width issmaller than that of the first openings, a process of performing firstetching using the etching mask as a mask to form openings in the hardmask, a process of performing second etching using at least the hardmask as a mask to form an opening between each color filter, and aprocess of forming a cap layer covering the opening formed between eachcolor filter to form an air gap between each color filter.

The solid state image pickup apparatus of the invention has a pluralityof color filters which are formed above the semiconductor substrate andcorrespond to each light receiving portion, a photoresist formed abovethe plurality of color filters, and side walls which are formed in sucha manner that one end contacts the side surfaces of the photoresist, inwhich a hollow portion is formed between each color filter, and thehollow portion is formed in alignment with the other end opposite to theone end in the side wall.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view illustrating an example of the schematic structureof a solid state image pickup apparatus (solid state image pickupdevice) according to a first embodiment of the invention.

FIGS. 2A to 2H are schematic views illustrating an example of a methodfor manufacturing the solid state image pickup apparatus (solid stateimage pickup device) according to the first embodiment of the invention.

FIG. 3A to 3G are schematic views illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to a second embodiment of the invention.

FIGS. 4A and 4B are schematic views illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to a third embodiment of the invention.

FIGS. 5A and 5B are schematic views illustrating an example of a methodfor manufacturing the solid state image pickup apparatus (solid stateimage pickup device) according to the fourth embodiment of theinvention.

FIGS. 6A to 6J are schematic views illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to a fifth embodiment of the invention.

FIG. 7 is an enlarged view illustrating a configuration of two pixels inthe solid state image pickup apparatus illustrated in FIG. 6E.

FIG. 8A to 8H are schematic views illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to a sixth embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, aspects (embodiments) for carrying out the invention aredescribed with reference to the drawings.

First Embodiment

First, a first embodiment of the invention is described.

FIG. 1 is a top view illustrating an example of the schematic structureof a solid state image pickup apparatus (solid state image pickupdevice) according to the first embodiment of the invention.

A solid state image pickup apparatus 100 according to this embodimenthas an image pickup region 110 and a peripheral region 120 other thanthe image pickup region.

The image pickup region 110 is a region in which pixels 111 are providedin a two-dimensional matrix shape. Each pixel 111 may contain aphotoelectric conversion portion, a wiring structure containing a wiringlayer and an interlayer insulating layer, a color filter, a microlens,and the like formed on a semiconductor substrate. For example, in thisembodiment, the pixels 111 of the image pickup region 110 are arrangedin a so-called Bayer pattern. In this case, for example, in a pixel row112 a and a pixel row 112 c, a pixel having a green (G) filter(hereinafter referred to as a “green pixel”), a pixel having a red (R)filter (hereinafter referred to as a “red pixel”), a green pixel, a redpixel, and a green pixel are sequentially arranged from the left side.In this case, in a pixel row 112 b, a pixel having a blue (B) filter(hereinafter referred to as a “blue pixel”), a green pixel, a bluepixel, a green pixel, and a blue pixel are sequentially arranged fromthe left side, for example.

Although this embodiment describes an example in which the pixels 111 ofthe image pickup region 110 are arranged in the Bayer arrangement butthe invention is not limited to this aspect and another arrangement maybe acceptable. Moreover, this embodiment describes an example in whichso-called primary color based color filters containing RGB are appliedas the color filter type but the invention is not limited to this aspectand so-called complementary color based color filters may be acceptable,for example.

The peripheral region 120 contains a light shielding filter 121, padelectrodes 122, and the like of a peripheral circuit portion.

Next, each process in a method for manufacturing a solid state imagepickup apparatus (solid state image pickup device) 100-1 according tothe first embodiment of the invention is described with reference toFIGS. 2A to 2H.

FIGS. 2A to 2H are schematic views illustrating an example of the methodfor manufacturing the solid state image pickup apparatus (solid stateimage pickup device) according to the first embodiment of the invention.The cross sectional views illustrated in FIGS. 2A to 2H are schematicviews illustrating the II-II cross section in the pixel row 112 billustrated in FIG. 1.

First, FIG. 2A is described.

First, a plurality of light receiving portions 21 are formed in atwo-dimensional matrix shape, for example, on the front surface (uppersurface) of a semiconductor substrate (hereinafter also simply referredto as a substrate) SB. Herein, the substrate SB is a silicon substrate,for example and the light receiving portion 21 is a photoelectricconversion element (photodiode), for example.

Subsequently, a multilayer wiring structure MI is formed on thesubstrate SB. This multilayer wiring structure MI is produced bysuccessively forming a first interlayer insulating layer 23 a, a firstwiring layer 22 a, a second interlayer insulating layer 23 b, a secondwiring layer 22 b, a third interlayer insulating layer 23 c, a thirdwiring layer 22 c, and a fourth interlayer insulating layer 23 d on thesubstrate SB, for example. In the example illustrated in FIG. 2A, theupper surface of the fourth interlayer insulating layer 23 d isplanarized but may not be planarized. More specifically, the uppersurface of the fourth interlayer insulating layer 23 d may beunevenness. Herein, the first interlayer insulating layer 23 a to thefourth interlayer insulating layer 23 d are collectively referred to as“interlayer insulating layers 23” and the first wiring layer 22 a to thethird wiring layer 22 c are collectively referred to as “wiring layers22”. The wiring layers 22 may be formed by a so-called damascene method(method including forming grooves in the interlayer insulating layers 23as the underground, and then embedding metal layers serving as thewiring layers 22 in the grooves) or may be formed by a so-called etchingmethod (a technique for forming metal layers on the interlayerinsulating layers 23 as the underground, and then pattern-forming themetal layers by etching). The interlayer insulating layers 23 are formedwith an inorganic material, such as silicon oxide, silicon nitride, orsilicon oxynitride, for example. In this embodiment, the interlayerinsulating layers 23 are formed with silicon oxide.

Subsequently, a first planarized layer 24 is formed on the multilayerwiring structure MI. The first planarized layer 24 is formed with, forexample, an acrylic resin based organic material.

Subsequently, a first color filter 25, a second color filter 26, and athird color filter 27 are formed on the first planarized layer 4 using aphotolithography method. Herein, each of the color filters 25 to 27 isprovided above light receiving portions 21 corresponding to each lightreceiving portion 21 and is formed with an acrylic resin based organicmaterial, for example. Herein, the color filters 25 to 27 are formed insuch a manner as to contact each other as illustrated in FIG. 2A. In theexample illustrated in FIG. 2A, the color filters 25 to 27 are formedwith the almost same film thickness but may be formed with a differentfilm thickness.

Subsequently, a second planarized layer 28 is formed on the colorfilters 25 to 27. The second planarized layer 28 is formed with anacrylic resin based organic material, for example.

Then, as illustrated in FIG. 2B, a photoresist 29 having an opening inthe upper region of the boundary portion of each of the color filters 25to 27 is formed on the second planarized layer 28 using aphotolithography method. Herein, the photoresist 29 contains a heatresistant material resistant to 200° C. or higher, for example. Thephotoresist 29 contains a material with a transmittance of light havinga wavelength of 400 nm to 700 nm of 80% or more, for example. In thedescription of the invention, the boundary region of each color filterrefers to a surface where each color filter contacts each other in thefilm thickness direction of each color filter. More specifically, in thecase where the color filters are formed in such a manner that an endportion of a certain color filter is overlapped with and covers an endportion of another color filter, a region where the end portions ofadjacent color filters are overlapped and covered with each other is notincluded in the boundary region in the invention.

Then, as illustrated in FIG. 2C, an oxide film 30 is formed over theentire surface including the upper surface and the side surfaces of thephotoresist 29 using a CVD method, for example. The oxide film 30 isformed with silicon oxide, for example and the film forming temperatureis about 200° C.

Then, as illustrated in FIG. 2D, the oxide film 30 is etched (etchedback) using an anisotropic dry etching method in such a manner as toleave the oxide film on the side surfaces (side walls) of thephotoresist 29 to form side walls 31 containing the oxide film. In thiscase, the side walls 31 are formed in such a manner as not to cover theupper region of the boundary portion of each of the color filters 25 to27 as illustrated in FIG. 2D. Gas used when etching back the oxide film30 is mixed gas of fluorocarbon gas, such as CF4, and Ar gas, forexample. The flow rates thereof are 12 [sccm] and 400 [sccm],respectively. As the fluorocarbon gas, other fluorocarbon gas other thanCF4, such as C2F6, may be used. With respect to rare gas, Ne, Kr, Xe,and the like other than Ar may be used. Other gas may be added asrequired. Although the example in which the side walls 31 are formedleaving the oxide film 30 only on the side surfaces (side walls) of thephotoresist 29 is shown in the example illustrated in FIG. 2, thisembodiment is not limited thereto. For example, the side walls 31 areformed leaving the oxide film 30 on the side surfaces (side walls) ofthe photoresist 29 and also the oxide film 30 may be left also on theupper surface of the photoresist 29. By leaving the oxide film 30 alsoon the upper surface of the photoresist 29 as described above, a hollowportion (air gap) 32 can be surely formed only between each of the colorfilters 25 to 27 from the selection ratio of the etching rate in theetching process illustrated in FIG. 2E which is the following process.

Subsequently, by etching using the photoresist 29 and the side walls 31(or the oxide film 30 left on the upper surface of the photoresist 29and the side walls 31) as a mask, the second planarized layer 28, eachof the color filters 25 to 27, and the first planarized layer 24 inportions which are not covered with the mask are removed as illustratedin FIG. 2E. More specifically, the boundary portion and the like of eachof the color filters 25 to 27 are removed. Thus, the hollow portion 32is formed between each of the color filters 25 to 27. In thisembodiment, dry etching is used as the etching illustrated in FIG. 2E.This dry etching is suitably a method with high directivity. As theetching conditions thereof, the selection ratio of the etching rate ofthe side walls 31 and each of the color filters 25 to 27 is suitablyhigh. The gas for use in the dry etching is oxygen gas, carbon monoxidegas, and nitrogen gas, for example. The flow rates thereof are 5 [sccm],80 [sccm], and 40 [sccm], respectively. In addition thereto, rare gas,such as Ar, may be added.

The film thickness of the oxide film 30 can be set as appropriateaccording to the width of the hollow portion 32 to be formed.

Then, the side walls 31 are removed as illustrated in FIG. 2F (when theoxide film 30 is left on the upper surface of the photoresist 9 in theprocess of FIG. 2D, the oxide film 30 is also removed with the sidewalls 31).

Then, as illustrated in FIG. 2G, a third planarized layer 33 is formedover the entire surface including the upper surface of the photoresist29 and the upper surface of the second planarized layer 28. The thirdplanarized layer 33 functions as a cap layer covering the openingregions of the hollow portions 32. For the third planarized layer 33, aninorganic material, such as silicon oxide or silicon nitride, forexample and an acrylic resin based organic material, for example, can beused. In this embodiment, the third planarized layer 33 is formed withan organic material.

Then, as illustrated in FIG. 2H, a microlens 34 corresponding to eachlight receiving portion 21 is formed on the third planarized layer 33 inthe upper region of each light receiving portion 21. The microlens 34 isformed with an acrylic resin based organic material, for example.

By passing through the processes described above of FIG. 2A to FIG. 2H,the solid state image pickup apparatus (solid state image pickup device)100-1 according to this embodiment is produced. In this embodiment, eachof the color filters 25 to 27 is formed using a photolithography methodbut the invention is not limited to this aspect.

In the first embodiment, first, the photoresist 29 having an opening inthe upper region of the boundary portion of each of the color filters 25to 27 is formed above each of the color filters 25 to 27. Then, the sidewalls 31 which do not cover the upper region of the boundary portion ofeach of the color filters 25 to 27 are formed on the side surfaces ofthe photoresist 29. Thereafter, the boundary portion of each of thecolor filters 25 to 27 is removed by etching using at least the sidewalls 31 as a mask to form the hollow portion 32 between each of thecolor filters 25 to 27.

According to this configuration, the hollow portions 32 are formed byetching using the side walls 31 formed on the side surfaces of thephotoresist 29 as a mask, and therefore the hollow portions 32 with anarrower width (for example, about 0.1 μm) can be formed. Thus, the areaoccupied by the color filter per pixel can be increased, so that thelight detection sensitivity by the light receiving portions 21 can beincreased.

Second Embodiment

Next, a second embodiment of the invention is described.

FIGS. 3A to 3G are schematic views illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to the second embodiment of theinvention. In FIGS. 3A to 3G, the same configurations as those ofillustrated in FIGS. 2A to 2H are designated by the same referencenumerals. The cross sectional views illustrated in FIGS. 3A to 3B areschematic views illustrating the III-III cross section in the pixel row112 b illustrated in FIG. 1.

Although FIG. 3A is the same as that of FIG. 2A in the first embodiment,FIG. 3A is described first.

First, a plurality of light receiving portions 21 are formed in atwo-dimensional matrix shape, for example, on the front surface (uppersurface) of the substrate SB. Herein, the substrate SB is a siliconsubstrate, for example and the light receiving portion 21 is aphotoelectric conversion element (photodiode), for example.

Subsequently, a multilayer wiring structure MI is formed on thesubstrate SB. This multilayer wiring structure MI is produced bysuccessively forming a first interlayer insulating layer 23 a, a firstwiring layer 22 a, a second interlayer insulating layer 23 b, a secondwiring layer 22 b, a third interlayer insulating layer 23 c, a thirdwiring layer 22 c, and a fourth interlayer insulating layer 23 d on thesubstrate SB, for example. In the example illustrated in FIG. 3A, theupper surface of the fourth interlayer insulating layer 23 d isplanarized but may not be planarized. More specifically, the uppersurface of the fourth interlayer insulating layer 23 d may beunevenness. Herein, the first interlayer insulating layer 23 a to theinterlayer insulating layer 23 d are collectively referred to as“interlayer insulating layers 23” and the first wiring layer 22 a to thethird wiring layer 22 c are collectively referred to as “wiring layers22”. The wiring layers 22 may be formed by a so-called damascene method(method including forming grooves in the interlayer insulating layers 23as the underground, and then embedding metal layers serving as thewiring layers 22 in the grooves) or may be formed by a so-called etchingmethod (a technique for forming metal layers on the interlayerinsulating layers 23 as the underground, and then pattern-forming themetal layers by etching). The interlayer insulating layers 23 are formedwith an inorganic material, such as silicon oxide, silicon nitride, orsilicon oxynitride, for example. In this embodiment, the interlayerinsulating layers 23 are formed with silicon oxide.

Subsequently, a first planarized layer 24 is formed on the multilayerwiring structure MI. The first planarized layer 24 is formed with, forexample, an acrylic resin based organic material.

Subsequently, a first color filter 25, a second color filter 26, and athird color filter 27 are formed on the first planarized layer 24 usinga photolithography method. Herein, each of the color filters 25 to 27 isprovided above light receiving portions 21 corresponding to each lightreceiving portion 21 and is formed with an acrylic resin based organicmaterial, for example. Herein, the color filters 25 to 27 are formed insuch a manner as to contact each other as illustrated in FIG. 3A. In theexample illustrated in FIG. 3A, the color filters 25 to 27 are formedwith the almost same film thickness but may be formed with a differentfilm thickness.

Subsequently, a second planarized layer 28 is formed on the colorfilters 25 to 27. The second planarized layer 28 is formed with anacrylic resin based organic material, for example.

Then, similarly as in FIG. 2B in the first embodiment, a photoresist 29having an opening in the upper region of the boundary portion of each ofthe color filters 25 to 27 is formed above the second planarized layer28 using a photolithography method as illustrated in FIG. 3B. Herein,the photoresist 29 contains a heat resistant material resistant to 200°C. or higher, for example. The photoresist 29 contains a material with atransmittance of light having a wavelength of 400 nm to 700 nm of 80% ormore, for example.

Then, similarly as in FIG. 2C in the first embodiment, an oxide film 30is formed over the entire surface including the upper surface and theside surfaces of the photoresist 29 using a CVD method, for example, asillustrated in FIG. 3C. The oxide film 30 is formed with silicon oxide,for example and the film forming temperature is about 200° C.

Then, similarly as in FIG. 2D in the first embodiment, the oxide film 30is etched back using an anisotropic dry etching method to leave theoxide film on the side surfaces (side walls) of the photoresist 29 toform side walls 31 containing the oxide film as illustrated in FIG. 3D.In this case, the side walls 31 are formed in such a manner as not tocover the upper region of the boundary portion of each of the colorfilters 25 to 27 as illustrated in FIG. 3D. Gas used when etching backthe oxide film 30 is CF4 and Ar, for example. The flow rates thereof are12 [sccm] and 400 [sccm], respectively. Although the example in whichthe side walls 31 are formed leaving the oxide film 30 only on the sidesurfaces (side walls) of the photoresist 29 is shown in the exampleillustrated in FIG. 3, this embodiment is not limited thereto. Forexample, the side walls 31 are formed leaving the oxide film 30 on theside surfaces (side walls) of the photoresist 29 and also the oxide film30 may be left also on the upper surface of the photoresist 29. Byleaving the oxide film 30 also on the upper surface of the photoresist29 as described above, a hollow portion 32 can be surely formed onlybetween each of the color filters 25 to 27 from the selection ratio ofthe etching rate in the etching process illustrated in FIG. 3E which isthe following process.

Subsequently, similarly as in FIG. 2E in the first embodiment, byetching using the photoresist 29 and the side walls 31 (or the oxidefilm 30 left on the upper surface of the photoresist 29 and the sidewalls 31) as a mask, the second planarized layer 28, each of the colorfilters 25 to 27, and the first planarized layer 24 in portions whichare not covered with the mask are removed as illustrated in FIG. 3E.More specifically, the boundary portion and the like of each of thecolor filters 25 to 27 are removed. Thus, the hollow portion 32 isformed between each of the color filters 25 to 27. In this embodiment,dry etching is used as the etching illustrated in FIG. 3E. This dryetching is suitably a method with high directivity. As the etchingconditions thereof, the selection ratio of the etching rate of the sidewalls 31 and each of the color filters 25 to 27 is suitably high. Thegas for use in the dry etching is oxygen gas, carbon monoxide gas, andnitrogen gas, for example. The flow rates thereof are 5 [sccm], 80[sccm], and 40 [sccm], respectively.

The film thickness of the oxide film 30 can be set as appropriateaccording to the width of the hollow portion 32 to be formed.

Then, as illustrated in FIG. 3F, a third planarized layer 33 is formedover the entire surface including the upper surface of the photoresist29 (or when the oxide film 30 is left on the upper surface of thephotoresist 29 in the process of FIG. 3D, the upper surface of the oxidefilm 30). The third planarized layer 33 functions as a cap layer sealingthe opening region of the hollow portions 32. For the third planarizedlayer 33, an inorganic material, such as silicon oxide or siliconnitride, for example and an acrylic resin based organic material, forexample, can be used. In this embodiment, the third planarized layer 33is formed with an organic material.

Then, as illustrated in FIG. 3G, a microlens 34 corresponding to eachlight receiving portion 21 is formed on the third planarized layer 33 inthe upper region of each light receiving portion 21. The microlens 34 isformed with an acrylic resin based organic material, for example.

By passing through the processes above of FIG. 3A to FIG. 3G, the solidstate image pickup apparatus (solid state image pickup device) 100-2according to this embodiment is produced. In this embodiment, each ofthe color filters 25 to 27 is formed using a photolithography method butthe invention is not limited to this aspect.

According to the second embodiment, the hollow portions 32 are formed byetching using the side walls 31 formed on the side surfaces of thephotoresist 29 as a mask, and therefore the hollow portions 32 with anarrower width (for example, about 0.1 μm) can be formed. Thus, the areaoccupied by the color filter per pixel can be increased, so that thelight detection sensitivity by the light receiving portions 21 can beincreased.

Moreover, in the second embodiment, since the removal process of theside walls 31 illustrated in FIG. 2F in the first embodiment is notperformed, the side walls 31 are formed in the solid state image pickupapparatus 100-2 according to the second embodiment. More specifically,in the solid state image pickup apparatus 100-2 according to the secondembodiment, the side walls 31 are formed in such a manner that one endcontacts the side surfaces of the photoresist 29 and the hollow portion32 is formed in alignment with the other end opposite to the one end inthe side walls 31.

Third Embodiment

Next, a third embodiment of the invention is described.

FIGS. 4A and 4B are schematics view illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to the third embodiment of the invention.In FIGS. 4A and 4B, the same configurations as those of illustrated inFIG. 2A to 2H are designated by the same reference numerals. The crosssectional views illustrated in FIGS. 4A and 4B are schematic viewsillustrating the IV-IV cross section in the pixel row 112 b illustratedin FIG. 1.

FIG. 4A is described.

In FIG. 4A, since the configuration of the substrate SB and the othercomponents are the same as those of FIG. 2A in the first embodiment, thedescription is omitted.

A plurality of light receiving portions 21 are formed on the frontsurface (upper surface) of the substrate SB, a multilayer wiringstructure MI′ is formed on the substrate SB as illustrated in FIG. 4A.In the multilayer wiring structure MI′ illustrated in FIG. 4A, alightguide (optical lightguide) 35 corresponding to each light receivingportion 21 is formed above each light receiving portion 21 in theinterlayer insulating layer 23 as compared the multilayer wiringstructure MI illustrated in FIG. 2A. This lightguide 35 is formed withsilicon nitride, for example, as an example. In the example illustratedin FIG. 4, although the insulating layer 23 (first interlayer insulatinglayer 23 a) is present between each light receiving portion 21 and thelightguide 35, this embodiment is limited to this embodiment. Forexample, the lightguide 35 which penetrates the interlayer insulatinglayer 23 to contact each light receiving portion 21 may be provided inthe interlayer insulating layer 23. By providing the lightguide 35 asdescribed, the light collecting efficiency to each light receivingportion 21 can be increased.

Subsequently, a first planarized layer 24 is formed on the multilayerwiring structure MI′ (on the interlayer insulating layer 23 and thelightguide 35).

Subsequently, a first color filter 25, a second color filter 26, and athird color filter 27 which are a plurality of color filter are formedon the first planarized layer 24 using a photolithography method, forexample. Herein, each of the color filters 25 to 27 is provided aboveeach light receiving portion 21 corresponding to each light receivingportion 21. Herein, each of the color filters 25 to 27 is formed in sucha manner as to contact each other as illustrated in FIG. 4A. In theexample illustrated in FIG. 4A, each of the color filters 25 to 27 isformed with the almost same film thickness but may be formed with adifferent film thickness.

Subsequently, a second planarized layer 28 is formed on each of thecolor filters 25 to 27.

Thereafter, by passing through each process of FIG. 2B to FIG. 2H in thefirst embodiment, a solid state image pickup apparatus (solid stateimage pickup device) 100-3 illustrated in FIG. 4B is produced.

According to the third embodiment, since each process of FIG. 2B to FIG.2E in the first embodiment is performed, the same operations and theeffects as those of the first embodiment can be obtained. Morespecifically, the hollow portions 32 with a narrower width (for example,about 0.1 μm) can be formed. Thus, the area occupied by the color filterper pixel can be increased, so that the light detection sensitivity bythe light receiving portions 21 can be increased.

Fourth Embodiment

Next, a fourth embodiment of the invention is described.

FIGS. 5A and 5B are schematic views illustrating an example of a methodfor manufacturing a solid state image pickup apparatus (solid stateimage pickup device) according to the fourth embodiment of theinvention. In FIGS. 5A and 5B, the same configurations as those ofillustrated in FIGS. 3A and 3G are designated by the same referencenumerals. The cross sectional views illustrated in FIGS. 5A and 5B areschematic views illustrating the V-V cross section in the pixel row 112b illustrated in FIG. 1.

FIG. 5A is described.

In FIG. 5A, since the configuration of the substrate SB and the othercomponents are the same as those of FIG. 3A in the second embodiment,the description is omitted.

A plurality of light receiving portions 21 are formed on the frontsurface (upper surface) of the substrate SB, a multilayer wiringstructure MI′ is formed on the substrate SB as illustrated in FIG. 5A.In the multilayer wiring structure MI′ illustrated in FIG. 5A, alightguide (optical lightguide) 35 corresponding to each light receivingportion 21 is formed above each light receiving portion 21 in theinterlayer insulating layer 23 as compared the multilayer wiringstructure MI illustrated in FIG. 3A. This lightguide 35 is formed withsilicon nitride, for example. In the example illustrated in FIG. 5,although the insulating layer 23 (first interlayer insulating layer 23a) is present between each light receiving portion 21 and the lightguide35, this embodiment is limited to this embodiment. For example, thelightguide 35 which penetrates the insulating layer 23 to contact eachlight receiving portion 21 may be provided in the interlayer insulatinglayer 23. By providing the lightguide 35 as described, the lightcollecting efficiency to each light receiving portion 21 can beincreased.

Subsequently, a first planarized layer 24 is formed on the multilayerwiring structure MI′ (above the interlayer insulating layer 23 and thelightguide 35).

Subsequently, a first color filter 25, a second color filter 26, and athird color filter 27 which are a plurality of color filter are formedon the first planarized layer 24 using a photolithography method, forexample. Herein, each of the color filters 25 to 27 is provided aboveeach light receiving portion 21 corresponding to each light receivingportion 21. Herein, each of the color filters 25 to 27 is formed in sucha manner as to contact each other as illustrated in FIG. 5A. In theexample illustrated in FIG. 5A, each of the color filters 25 to 27 isformed with the almost same film thickness but may be formed with adifferent film thickness.

Subsequently, a second planarized layer 28 is formed on each of thecolor filters 25 to 27.

Thereafter, by passing through each process of FIG. 3B to FIG. 3G in thesecond embodiment, a solid state image pickup apparatus (solid stateimage pickup device) 100-4 illustrated in FIG. 5B is produced.

According to the fourth embodiment, since each process of FIG. 3B toFIG. 3E in the second embodiment is performed, the same operations andthe effects as those of the second embodiment can be obtained. Morespecifically, the hollow portions 32 with a narrower width (for example,about 0.1 μm) can be formed. Thus, the area occupied by the color filterper pixel can be increased, so that the light detection sensitivity bythe light receiving portions 21 can be increased.

Moreover, in the fourth embodiment, since the removal process of theside walls 31 illustrated in FIG. 2F in the first embodiment is notperformed, the side walls 31 are formed in the solid state image pickupapparatus 100-4 according to the fourth embodiment. More specifically,in the solid state image pickup apparatus 100-4 according to the fourthembodiment, the side walls 31 are formed in such a manner that one endcontacts the side surfaces of the photoresist 29 and the hollow portion32 is formed in alignment with the other end opposite to the one end inthe side walls 31.

Fifth Embodiment

Next, each process in a method for manufacturing a solid state imagepickup apparatus (solid state image pickup device) 100 according to afifth embodiment of the invention is described with reference to FIGS.6A to 6J.

FIGS. 6A to 6J are cross sectional views illustrating an example of themethod for manufacturing the solid state image pickup apparatus (solidstate image pickup device) according to the fifth embodiment of theinvention. The cross sectional views illustrated in FIGS. 6A to 6J areschematic views illustrating the VI-VI cross section in the pixel row112 b illustrated in FIG. 1.

In FIGS. 6A to 6J, the illustration of the wiring layers and interlayerinsulation films which are illustrated in the description of theabove-described embodiments is omitted.

In a process illustrated in FIG. 6A, first, a plurality of lightreceiving portions 41 are formed on the front surface (upper surface) ofthe substrate SB in a two-dimensional matrix shape, for example.

Subsequently, green filters 45 are formed on the light receivingportions 41 of green pixel formation regions using a photolithographymethod.

Then, in a process illustrated in FIG. 6B, blue filters 46 are formed onthe light receiving portions 41 of blue pixel formation regions using aphotolithography method.

Subsequently, red filters (not illustrated in FIG. 6) are formed on thelight receiving portions 41 of red pixel formation regions (formationregions of the red pixels of the pixel row 112 a and the pixel row 112 cillustrated in FIG. 1) using a photolithography method. Herein, eachcolor filter in the plurality of color filters is formed in such amanner as to contact each other. Each color filter is formed with anorganic material, such as acrylic resin, for example.

In the example illustrated in FIG. 6A and FIG. 6B, the blue filters 46and the red filters (not illustrated in FIG. 6) are formed after theformation of the green filters 45, but the order of the processes may bechanged to form each color filter. Thus, in this embodiment, a pluralityof color filters corresponding to each light receiving portion in theplurality of light receiving portions 41 are formed above the substrateSB.

Then, in a process illustrated in FIG. 6C, a hard mask 48 is formed oneach color filter including the green filters 45, the blue filters 46,and the red filters (not illustrated in FIG. 6D). This hard mask 48 isformed using a low temperature plasma CVD method, for example, andcontains inorganic materials, such as silicon oxide, silicon nitride,and silicon oxynitride, for example. In this case, the film formingtemperature of the hard mask 48 is suitably in the range of 150° C. to220° C. Since the hard mask 48 is not removed in the following processand remains, a material with high transmittance which does not allow areduction in sensitivity characteristics of the solid state image pickupapparatus 100 is desirable.

Then, in a process illustrated in FIG. 6D, a resist pattern 49 having afirst opening 51 which opens in the upper region of the boundary portionof each color filter is formed on the hard mask 48 using aphotolithography method. Herein, the width of the first openings 51 isdefined as W1. As a material of the resist for forming the resistpattern 49, an organic material, such as novolac resin, styrene resin,or acrylic resin, is mentioned, for example. As the resist for formingthe resist pattern 49, a resist for use in the formation of a microlensis suitable because the resist pattern 49 is heated and fluidized in thefollowing process.

Then, in a process illustrated in FIG. 6E, an etching mask 53 havingsecond openings 55 whose width is smaller than the width of the firstopenings 51 is formed by heat-treating the resist pattern 49 in twostages. The etching mask 53 is a mask for dry etching the hard mask 48and the boundary portion of each color filter below the hard mask 48.

Hereinafter, the two-stage heat treatment performed to the resistpattern 49 is described.

First, in the first stage of the heat treatment, by applying atemperature equal to or higher than the softening point of the resistpattern 49 illustrated in FIG. 6D, the resist pattern 49 is heated andfluidized to form the second openings 55 having a width W2 smaller thana width W1 of the first openings 51 (W2<W1). Since the line width (W2)smaller than the resolution line width (W1) by a photolithography methodillustrated in FIG. 6 can be formed by the heat treatment of the heatingand fluidizing, the width of hollow portions to be formed in and afterthe following process can be made small. When the width of the air gapis large relative to the dimension of one pixel, light entering thelight receiving portions 41 decreases, which becomes a factor ofworsening the sensitivity characteristics of the solid state imagepickup apparatus 100. Therefore, it is important to make the width ofthe air gap small.

Subsequently, in the second stage of the heat treatment, a temperaturehigher than the temperature of the first stage of the heat treatment isapplied to thereby accelerate a crosslinking reaction of the resist andstabilize the same.

As described above, the etching mask 53 is a mask for dry etching thehard mask 48 and the boundary portion of each color filter below thehard mask 48. When arranging the etching mask on the surface of amaterial to be etched and performing anisotropic etching, such as dryetching, it is known that the shape after the etching is affected by theinclined surface of the etching mask. Specifically, this is becauseetching species (reactive ion and the like) incident to a material to beetched includes an etching species reflecting after hitting the inclinedsurface of the etching mask. Therefore, when the end portion of theetching mask 53 is inclined, the etching progress direction is affectedby the inclination of the etching mask 53, so that the etching proceedsobliquely downward. Therefore, as illustrated in FIG. 6E, when theetching masks 53 facing each other have an inclined surface, the etchingshape is tapered depending on the degree of the inclination, so thatthere may arise a problem in that the color filters cannot be separatedand the etching stops in the middle of the etching.

FIG. 7 is a cross sectional view in which the configuration of 2 pixelsillustrated in FIG. 6E is enlarged.

In the case of this embodiment, in order to solve the above-describedproblems, the etching mask 53 is formed in such a manner that the angle(θ1) formed by the tangent on the inclined surface at the end portion ofthe etching mask 53 and the tangent on the upper surface (front surface)of the hard mask 48 illustrated in FIG. 7 is 76° or more.

Then, in a process illustrated in FIG. 6F, an opening 57 is formed inthe upper region of the boundary portion of each color filter in thehard mask 48 by etching (first etching) using the etching mask 53 as amask. The openings 57 reflect the openings 55. The etching of the hardmask 48 is performed using fluorocarbon gas, such as CF4, mixed gas offluorocarbon gas and oxygen gas, or mixed gas of fluorocarbon gas,oxygen gas, and nitrogen gas as etching gas, for example.

Then, in a process illustrated in FIG. 6G, the opening 59 is formed inthe boundary portion of each color filter by etching (second etching)using the hard mask 48 (further etching mask 53) as a mask. The openings59 reflect the openings 57. The etching (second etching) of the colorfilter is formed, for example, using mixed gas of oxygen gas, carbonmonoxide gas, and nitrogen gas as etching gas under the conditions wherethe selection ratio of the hard mask 48 and the color filter issufficiently secured. The etching mask 53 is removed simultaneously withperforming the etching of the color filters (second etching). Herein,since the color filters other than the regions of the openings 57 arecovered with the hard mask 48, the color filters other than the regionsof the openings 59 can be prevented from being damaged in the etchingprocess illustrated in FIG. 6G.

Then, in a process illustrated in FIG. 6H, a cap layer 61 is formed onthe entire surface including the upper surface of the hard mask 48 tocover the openings 59 to thereby form a hollow portion 63 between eachcolor filter. The cap layer 61 is formed using a low temperature plasmaCVD method, for example, and contains inorganic materials, such assilicon oxide, silicon nitride, and silicon oxynitride, for example. Inthis case, the film forming temperature of the cap layer 61 is suitablyin the range of 150° C. to 220° C. It is desirable that the hard mask 48and the cap layer 61 contain the same material or a material with thesame refractive index. When the materials of the hard mask 48 and thecap layer 61 are different from each other, the refractive indices aredifferent from each other in many cases. Therefore, reflection occurs onthe interface between the hard mask 48 and the cap layer 61, which maybecome a factor of worsening the sensitivity characteristics of thesolid state image pickup apparatus 100.

Then, in a process illustrated in FIG. 6I and FIG. 6J, a microlens 69 isformed on the cap layer 61 in such a manner as to correspond to thecolor filter of each pixel.

In the formation of the microlens 69, first, an organic layer 65containing an organic material is formed on the cap layer 61, and then alens shape portion 67 containing an organic material is formed on theorganic layer 65 as illustrated in FIG. 6I. Thereafter, the organiclayer 65 is etched with the lens shape portion 67, whereby themicrolenses 69 of FIG. 6J having a convex surface following the shape ofthe convex of the lens shape portion 67 are formed.

When an oblique light a illustrated in FIG. 6J enters the microlenses 69in this embodiment, the light a transmits the microlenses 69, the caplayer 61, and the hard mask 48, and then transmits the color filters,such as the green filter 45, for example. The light a is divided into alight reflecting on the side walls (in the example illustrated in FIG.6J, an interface of the green filter 45 and the air gap 63) of the colorfilter and a light refracting without reflecting on the side walls, andthe oblique light a is difficult to enter the other light receivingportions 41 adjacent thereto. Thus, when the oblique light a isdifficult to enter the other light receiving portions 41 adjacentthereto, color mixing resulting from the oblique light a becomesdifficult to occur.

In the method for manufacturing the solid state image pickup apparatusaccording to this embodiment, the hard mask 48 is formed on each colorfilter, and the resist pattern 49 having the first opening 51 is formedon the hard mask 48. The first opening 51 is in the upper region of theboundary portion of each color filter. Then, the resist pattern 49 isheat treated to thereby form the etching mask 53 having the secondopenings 55 whose width is smaller than that of the first openings 51.Then, the first etching using the etching mask 53 as a mask is performedto form the opening 57 in the hard mask 48. The opening 57 is in theupper region of the boundary portion of each color filter. Then, thesecond etching using at least the hard mask 48 as a mask is performed toform the opening 59 between each color filter. Thereafter, the cap layer61 covering the openings 59 is formed to form the hollow portion 63 inthe boundary portion of each color filter.

According to the method for manufacturing the solid state image pickupapparatus, the process of removing the hard mask formed in order to formthe color filters and the process of performing the entire surface etchback or chemical mechanical polishing (CMP) for removing the uppersurface of the color filters described in, for example, Japanese PatentLaid-Open No. 2006-295125 are unnecessary. Thus, an increase in thenumber of processes when patterning the color filters can be suppressed,so that a reduction in manufacturing cost and productivity can besecured.

Furthermore, according to the method for manufacturing the solid stateimage pickup apparatus, etching is performed in the state where theupper portions in portions other than the boundary portion of the colorfilters are covered with the hard mask to form the hollow portionbetween each color filter, the hollow portion can be suitably formedbetween each color filter while preventing damages to the color filters.

Sixth Embodiment

Next, a sixth embodiment of the invention is described.

The top view illustrating the schematic structure of a solid state imagepickup apparatus (solid state image pickup device) according to thesixth embodiment is the same as the top view illustrating the schematicstructure of the solid state image pickup apparatus 100 according to thefirst embodiment illustrated in FIG. 1.

Next, each process in a method for manufacturing a solid state imagepickup apparatus (solid state image pickup device) 100 according to thesixth embodiment of the invention is described with reference to FIGS.8A to 8H.

FIGS. 8A to 8H are cross sectional views illustrating an example of themethod for manufacturing the solid state image pickup apparatus (solidstate image pickup device) according to the sixth embodiment of theinvention. The cross sectional views illustrated in FIGS. 8A to 8H areschematic views illustrating the VIII-VIII cross section in the pixelrow 112 b illustrated in FIG. 1. In FIGS. 8A to 8H, the sameconfigurations as those of illustrated in FIGS. 6A to 6J in the fifthembodiment are designated by the same reference numerals. In FIGS. 8A to8H, the illustration of the wiring layers and interlayer insulationfilms which are illustrated in the description of the above-describedembodiments is omitted similarly as in FIGS. 6A to 6J.

In a process illustrated in FIG. 8A, first, a plurality of lightreceiving portions 41 are formed on the front surface (upper surface) ofthe substrate SB in a two-dimensional matrix shape, for example.

Subsequently, green filters 45 are formed on the light receivingportions 41 of green pixel formation regions using a photolithographymethod.

Then, blue filters 46 are formed on the light receiving portions 41 ofblue pixel formation regions using a photolithography method.

Subsequently, red filters (not illustrated in FIG. 8) are formed on thelight receiving portions 41 of red pixel formation regions (formationregions of the red pixels of the pixel row 112 a and the pixel row 112 cillustrated in FIG. 1) using a photolithography method. Herein, eachcolor filter is formed in such a manner as to contact each other. Eachcolor filter is formed with an organic material, such as acrylic resin,for example. The thickness (i.e., upper surface height of each colorfilter) of each color filter is different from each other.

Thus, in this embodiment, a plurality of color filters corresponding toeach light receiving portion in the plurality of light receivingportions 41 are formed above the substrate SB.

Then, a planarized layer 71 is formed on each color filter including thegreen filters 45, the blue filters 46, and the red filters (notillustrated in FIG. 8). This planarized layer 71 is effective for thecase where the thickness (i.e., upper surface height of each colorfilter) of each color filter is different from each other and there is alevel difference between each color filter. More specifically, when thelevel difference between each color filter is not planarized, there is apossibility that the hard mask to be formed in the following process isnot planarized and the etching mask and the like to be formed in thefollowing process are not normally formed. Therefore, it is effective toprovide the planarized layer 71. For the planarized layer 71, a materialwith a high transmittance is desirable and contains, for example, anorganic material, such as acrylic resin, novolac resin, or styreneresin.

In the example described above, the blue filters 46 and the red filters(not illustrated in FIG. 8) are formed after the formation of the greenfilters 45, but the order of the processes may be changed to form eachcolor filter.

Then, in a process illustrated in FIG. 8B, the hard mask 48 is formed onthe planarized layer 71. This hard mask 48 is formed using a lowtemperature plasma CVD method, for example, and contains inorganicmaterials, such as silicon oxide, silicon nitride, and siliconoxynitride, for example. In this case, the film forming temperature ofthe hard mask 48 is suitably in the range of 150° C. to 220° C. Sincethe hard mask 48 is not removed in the following process and remains, amaterial with high transmittance which does not allow a reduction insensitivity characteristics of the solid state image pickup apparatus100 is desirable.

Then, in a process illustrated in FIG. 8C, a resist pattern 49 having afirst opening 51 which opens in the upper region of the boundary portionof each color filter is formed on the hard mask 48 using aphotolithography method. Herein, the width of the first openings 51 isdefined as W1. As a material of the resist for forming the resistpattern 49, an organic material, such as novolac resin, styrene resin,or acrylic resin, is mentioned, for example. As the resist for formingthe resist pattern 49, a resist for use in the formation of a microlensis suitable because the resist pattern 49 is heated and fluidized in thefollowing process.

Then, in a process illustrated in FIG. 8D, an etching mask 53 havingsecond openings 55 whose width is smaller than the width of the firstopenings 51 is formed by heat-treating the resist pattern 49 in twostages. The etching mask 53 is a mask for dry etching the hard mask 48and the boundary portion of each color filter present below the hardmask 48.

Hereinafter, the two-stage heat treatment performed to the resistpattern 49 is described.

First, in the first stage of the heat treatment, by applying atemperature equal to or higher than the softening point of the resistpattern 49 illustrated in FIG. 8C, the resist pattern 49 is heated andfluidized to form the second openings 55 having a width W2 smaller thana width W1 of the first openings 51 (W2<W1). Since the line width (W2)smaller than the resolution line width (W1) by a photolithography methodillustrated in FIG. 8C can be formed by the heat treatment of theheating and fluidizing, the width of hollow portions to be formed in andafter the following process can be made small. When the width of thehollow portion is large relative to the dimension of one pixel, lightentering the light receiving portions 41 decreases, which becomes afactor of worsening the sensitivity characteristics of the solid stateimage pickup apparatus 100. Therefore, it is important to make the widthof the air gap small.

Subsequently, in the second stage of the heat treatment, a temperaturehigher than the temperature of the first stage of the heat treatment isapplied to thereby accelerate a crosslinking reaction of the resist andstabilize the same.

Also in the case of this embodiment, the etching mask 53 is formed onsuch a manner that the angle (θ1) formed by the tangent in the inclinedsurface at the end portion of the etching mask 53 and the tangent on theupper surface (front surface) of the hard mask 48 illustrated in FIG. 7is 76° or more similarly as in the case of the above-described fifthembodiment.

Then, in a process illustrated in FIG. 8E, an opening 57 is formed inthe upper region of the boundary portion of each color filter in thehard mask 48 by etching (first etching) using the etching mask 53 as amask. The openings 57 reflect the openings 55. The etching of the hardmask 48 is performed using fluorocarbon gas, such as CF4, mixed gas offluorocarbon gas and oxygen gas, or mixed gas of fluorocarbon gas,oxygen gas, and nitrogen gas as etching gas, for example.

Then, in a process illustrated in FIG. 8F, an opening 59 is formed inthe upper region of the boundary portion of each color filter in theplanarized layer 71 and between each color filter by etching (secondetching) using the hard mask 48 (further etching mask 53) as a mask. Theopenings 59 reflect the openings 57. The etching (second etching) ofthis planarized layer 71 and the color filters is performed using, forexample, mixed gas of oxygen gas, carbon monoxide gas, and nitrogen gasas etching gas under the conditions where the selection ratio of thehard mask 48 and the planarized layer 71 and the color filter issufficiently secured. The etching mask 53 is removed simultaneously withperforming the etching (second etching) of this planarized layer 71 andthe color filters. Herein, since the planarized layer 71 and the colorfilters other than the regions of the openings 59 are covered with thehard mask 48, the planarized layer 71 and the color filters other thanthe regions of the openings 59 can be prevented from being damaged inthe etch process illustrated in FIG. 8F.

Then, in a process illustrated in FIG. 8G, a cap layer 61 is formed onthe entire surface including the upper surface of the hard mask 48 tocover the openings 59 to thereby form a hollow portion 63 between eachcolor filter. The cap layer 61 is formed using a low temperature plasmaCVD method, for example, and contains inorganic materials, such assilicon oxide, silicon nitride, and silicon oxynitride, for example. Inthis case, the film forming temperature of the cap layer 61 is suitablyin the range of 150° C. to 220° C. It is desirable that the hard mask 48and the cap layer 61 contain the same material or a material with thesame refractive index.

Then, in a process illustrated in FIG. 8H, a microlens 69 is formed onthe cap layer 61 in such a manner as to correspond to the color filterof each pixel. In the formation of the microlens 69, first, an organiclayer 65 containing an organic material is formed on the cap layer 61,and then a lens shape portion 67 containing an organic material isformed on the organic layer 65 as illustrated in FIG. 8H. Thereafter,the organic layer 65 is etched with the lens shape portion 67, wherebythe microlenses 69 of FIG. 8H having a convex surface following theshape of the convex of the lens shape portion 67 are formed.

According to the method for manufacturing the solid state image pickupapparatus according to this embodiment, the same operations and the sameeffects as the operations and the effects of the methods formanufacturing the solid state image pickup apparatus according to thefirst to fifth embodiments described above are demonstrated. Morespecifically, the air gap can be suitably formed between each colorfilter while suppressing an increase in the number of processes whenpatterning the color filters.

Other Embodiments

Moreover, in the solid state image pickup apparatus (solid state imagepickup device) 100 according to the first to sixth embodiments describedabove, an inner lens (interlayer lens) corresponding to each lightreceiving portion 21 may be provided between the multilayer wiringstructure (interlayer insulating layer 23) and the first planarizedlayer 24. As an example, convex inner lenses containing silicon nitride,for example, are provided. Thus, by providing the inner lenses tothereby use the inner lenses and the microlenses 34 in combination, thelight collecting efficiency to each light receiving portion 21 can beincreased.

Moreover, in the solid state image pickup apparatus (solid state imagepickup device) 100 according to the first to sixth embodiments describedabove, the second planarized layer 28 is formed on each of the colorfilters 25 to 27 but the second planarized layer 28 may not be formed.

Each embodiment of the invention described above simply describes aspecific example when enforcing the invention and the technical scope ofthe invention is not limited. More specifically, the invention can beenforced in various aspects without deviating from the technical idea orthe main feature thereof.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2013-005601 filed Jan. 16, 2013 and No. 2013-045677 filed Mar. 7, 2013,which are hereby incorporated by reference herein in their entirety.

What is claimed is:
 1. A method for manufacturing a solid state imagepickup apparatus in which a plurality of light receiving portions areprovided on a semiconductor substrate, comprising: forming a pluralityof color filters corresponding to each light receiving portion above thesemiconductor substrate in such a manner as to contact each other;forming a photoresist having openings above the plurality of colorfilters; forming side walls on side surfaces of the photoresist; andforming a hollow portion between each color filter by performing etchingusing at least the side walls as a mask.
 2. The method for manufacturinga solid state image pickup apparatus according to claim 1, furthercomprising forming a cap layer covering the hollow portions.
 3. Themethod for manufacturing a solid state image pickup apparatus accordingto claim 1, wherein the photoresist contains a heat resistant materialresistant to 200° C. or higher.
 4. The method for manufacturing a solidstate image pickup apparatus according to claim 1, wherein thephotoresist contains a material whose transmittance of light having awavelength of 400 nm to 700 nm is 80% or more.
 5. The method formanufacturing a solid state image pickup apparatus according to claim 1,wherein, in the formation of the side walls, an oxide film is formed onthe entire surface including an upper surface and the side surfaces ofthe photoresist, and then the oxide film is etched using an anisotropicdry etching method in such a manner as to leave the oxide film on theside surfaces of the photoresist to form the side walls.
 6. The methodfor manufacturing a solid state image pickup apparatus according toclaim 5, wherein, in the formation of the side walls, the oxide film isleft also on the upper surface of the photoresist.
 7. The method formanufacturing a solid state image pickup apparatus according to claim 5,wherein gas for use in the etching in the formation of the hollowportions is oxygen gas, carbon monoxide gas, and nitrogen gas, and gasfor use in the etching of the oxide film is fluorocarbon gas and argongas.
 8. The method for manufacturing a solid state image pickupapparatus according to claim 1, further comprising forming a microlenscorresponding to each light receiving portion above each color filter inthe plurality of color filters.
 9. The method for manufacturing a solidstate image pickup apparatus according to claim 1, further comprisingforming a lightguide corresponding to each light receiving portion inthe plurality of light receiving portions above the semiconductorsubstrate, wherein the plurality of color filters are formed above theplurality of lightguides.
 10. A method for manufacturing a solid stateimage pickup apparatus in which a plurality of light receiving portionsare provided on an upper surface of a semiconductor substrate,comprising: forming a plurality of color filters corresponding to eachlight receiving portion in such a manner as to contact each other abovethe semiconductor substrate; forming a hard mask on the plurality ofcolor filters; forming a resist pattern having first openings on thehard mask; heat treating the resist pattern to form an etching maskhaving second openings whose width is smaller than that of the firstopenings; performing first etching using the etching mask as a mask toform openings in the hard mask; performing second etching using at leastthe hard mask as a mask to form an opening between each color filter;and forming a cap layer covering the opening formed between each colorfilter to form an air gap between each color filter.
 11. The method formanufacturing a solid state image pickup apparatus according to claim10, wherein, by the second etching, the etching mask is removedsimultaneously with the formation of the opening between each colorfilter.
 12. The method for manufacturing a solid state image pickupapparatus according to claim 10, wherein the hard mask and the cap layercontain a same material or a material with a same refractive index. 13.The method for manufacturing a solid state image pickup apparatusaccording to claim 10, wherein the hard mask and the cap layer containsilicon oxide, silicon nitride, or silicon oxynitride.
 14. The methodfor manufacturing a solid state image pickup apparatus according toclaim 10, further comprising forming a planarized layer between theplurality of color filters and the hard mask, wherein, by the secondetching, an opening is formed between each color filter and alsoopenings are formed in the planarized layer.
 15. The method formanufacturing a solid state image pickup apparatus according to claim10, wherein the etching mask is formed in contact with an upper surfaceof the hard mask, and an angle formed by a tangent on an inclinedsurface of an end portion where the side walls of the etching maskcontact the hard mask and the upper surface of the hard mask is 76° ormore.
 16. A method for manufacturing a solid state image pickupapparatus in which a plurality of light receiving portions are providedon an upper surface of a semiconductor substrate, comprising: aplurality of color filters formed above the semiconductor substrate andcorresponding to each light receiving portion; a photoresist formed onthe plurality of color filters; and side walls formed in such a mannerthat one end contacts side surfaces of the photoresist; a hollow portionbeing formed between each color filter, and the hollow portion beingformed in alignment with another end opposite to the one end in the sidewalls.